This invention relates to a dock leveler used to bridge the gap between a loading dock and the bed of a truck or carrier parked adjacent the loading dock, and more particularly to improvements in dock levelers incorporating an airbag or other inflatable member for raising the ramp of the dock leveler.
A dock leveler typically includes a frame or supporting structure mounted in a pit or depression in the loading dock. The rear end of a ramp or deck plate is pivotally mounted to the supporting structure so that the ramp is movable from a horizontal position to a position within the working range of the ramp (e.g., between an upwardly inclined position and a downwardly declined position). An extension lip is pivotably mounted to the forward end of the ramp, and is movable between a downwardly hanging pendant position and an extended position in which the lip forms an extension to the ramp.
After a truck has parked in front of the loading dock in preparation for a loading or unloading operation, the ramp of the dock leveler is raised to its upwardly inclined position. The lip is then pivoted outwardly to its extended position. As the ramp is lowered, the lip engages the bed of the truck to support the ramp, such that the ramp and the lip in combination bridge the gap between the loading dock and the truck bed. After the loading or unloading operation is completed, the ramp is raised and the lip falls by gravity to its pendant position. The ramp is then lowered to its horizontal position, and the truck can then pull away from the loading dock.
In the past, the ramp has been pivoted to its upward position in response to operation of a mechanical or hydraulic mechanism. However, recent developments in the dock leveler art disclose an inflatable member or bag utilized to pivot the ramp to its upwardly inclined position, such as is illustrated in U.S. Pat. No. 5,802,650. This patent discloses a bag inflated with low-pressure air by an inflating device such as a fan or blower, and is hereby incorporated by reference in its entirety.
Dock leveler users have different preferences as to size and power units for their dock levelers, necessitating a dock leveler distributor to carry a wide variety of stock items to match a large number of combinations.
The present invention relates to improvements to the above-noted dock levelers incorporating an inflatable member. In one aspect, the dock leveler of the present invention is adapted to be mounted to a loading dock having an upper dock surface and a pit disposed in the upper surface. The dock leveler includes a supporting structure positionable within the pit, the pit having a floor, the supporting structure including at least two vertical members, each vertical member having therethrough at least one horizontally-oriented bore. The dock leveler also includes a ramp having a rear edge movably interconnected with the supporting structure at a pivot point; at least two hook-type bracket members affixed to the rear edge of the ramp; and a power unit positioned to cause relative movement between the ramp and the pit floor upon operation of the power unit, thereby resulting in movement of the ramp relative to the supporting structure.
In one embodiment, the power unit is an inflatable assembly and can include an intermediate member pivotably mounted to the hook-type bracket members. The intermediate member includes a roller member mounted to an end of the intermediate member. In another embodiment, the inflatable assembly includes a blower device operatively connected to the inflatable assembly. In yet another embodiment, the power unit is a hydraulic assembly having a hydraulic cylinder and can include a support frame removably mounted to the at least two vertical members using attachment devices in the bores. The support frame can be affixed to the pit floor, and the hydraulic cylinder can be pivotably attached to the support frame and to the ramp. Finally, the hydraulic assembly can include a hydraulic pump operatively connected to the hydraulic cylinder.
In yet another embodiment, the dock leveler includes structure to accommodate both hydraulic and pneumatic power units, allowing the same dock leveler structure to be used with either power unit, thus reducing the number of stock keeping units that need to be manufactured and carried.